human evolution

What is it, exactly, that distinguishes us from other species? The definition of humankind has perplexed scientists, philosophers and theorists for centuries. DNA composition differentiates species in a technical sense, but that definition is hardly satisfying. Certainly there must be something more ethereal that separates us from “lower” forms of creatures. Over the centuries, several definitions have emerged — from using tools to speaking — but have then been proven insufficient in some heuristic way. So I propose another option: manipulating energy.

The sequencing of the Neanderthal genome in 2010 helps scientists answer the age-old question

Modern humans reached the islands of Southeast Asia by approximately 50,000 years ago, but our ancestors’ journey was not easy. Even during times of low sea level, a voyage to some of these islands would have required crossing open water, leaving many scientists to wonder how humans arrived on the most isolated islands.

Last October, scientists formally introduced the world to Ardi the Ardipithecus, the well-preserved skeleton of a 4.4-million-year-old hominin found in Ethiopia. Eight months later, scientists have had time to digest the data from all 11 papers that were published in Science last fall regarding Ardi’s biology and ecology, and there is some dissent.

Did “Clan of the Cave Bear” get it right after all?

Probably not, but at least one aspect of the ice age saga is true: Modern humans interbred with Neanderthals. In fact, for many of us, as much as 4 percent of our DNA may be Neanderthal DNA. That’s the conclusion of a group of 56 scientists who have just announced today in Science that they’ve completed a draft sequence of the Neanderthal genome.

Last month, the Smithsonian’s National Museum of Natural History in Washington, D.C., unveiled its new (permanent) human evolution exhibit: the David H. Koch Hall of Human Origins. The exhibit seeks to answer the millennia-old question, What does it mean to be human?

Modern humans and Neanderthals lived side by side on the Eurasian landscape for tens of thousands of years — but it turns out they weren’t alone, much to researchers’ surprise. A team of researchers has found a hominin bone in a Siberian cave containing DNA that doesn’t match up with either known hominin species at that time, the researchers reported in Nature today, indicating that these humans shared the continent with a third, unknown hominin.

At 4.4 million years old, Ardipithecus ramidus is not the oldest known hominid. In 2002, scientists announced they had discovered a hominid skull from the Sahel region of Chad. Named Sahelanthropus tchadensis, the species dates to about 7 million years ago. And a few years earlier, scientists had announced the discovery of several hominid fossils, including a thigh bone, in Kenya that dated to about 6 million years ago. They named the species Orrorin tugenensis.

Though counterintuitive, scientists have turned their attention away from the feet and to the wrist and forearm to better understand how humans evolved upright walking, or bipedalism. African apes are humans’ closest living relatives, and because these apes knuckle-walk, some paleoanthropologists have suggested that African apes and humans share a knuckle-walking ancestor. A new study, however, reveals that lumping the locomotion of all African apes together is a mistake: Knuckle-walking may have evolved more than once in the ape lineage.

Lucy, the 3.2-million-year-old Australopithecus afarensis fossil, has long been the poster child for early human evolution. But now she’ll have to share the spotlight with an even older hominid. After spending the last 15 years studying an ancient hominid species about the size of a chimpanzee, scientists revealed details about the 4.4-million-year-old Ardipithecus ramidus in a press conference today.

A squirrel-sized primate that lived 47 million years ago in the rainforests of Europe may be the common ancestor of monkeys, apes and humans, according to scientists who announced the discovery of the “missing link” fossil yesterday at a press conference. The well-preserved fossil has been at the center of a whirlwind PR blitz, including a History Channel documentary airing next week and an upcoming book — yet some scientists say the bones don’t live up to the hype.

Mapping out how one species of early hominin branches to another has always been complicated by the rarity of complete specimens and lack of precise dating methods for fossils more than 50,000 years old. Now researchers studying the braincase, pelvis, hands and feet of a primitive hominin — which lived about the same time early Homo species were evolving — are taking full advantage of a rare, nearly complete assemblage of fossils and a new highly accurate dating method to once again redraw humankind’s ancient lineage.